Process for the preparation of 2-(2&#39;,2&#39;,2&#39;-trihalogenoethyl)-4-halogenocyclobutan-1-ones

ABSTRACT

A process for the preparation of 2-(2&#39;,2&#39;,2&#39;,-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formula ##STR1## in which one of the radicals R 1  and R 2  is methyl and the other is hydrogen or methyl, or R 1  and R 2  together are an alkylene group having 2 to 4 carbon atoms, and X and Y are each chlorine or bromine, comprising reacting a 2,4,4,4-tetrahalogenobutyric acid chloride in the presence of an organic base with an ethylene compound which is disubstituted in 1-position by the radicals R 1  and R 2 , as defined above, to form a 2-(2&#39;,2&#39;,2&#39;-trihalogenoethyl)-2-halogenocyclobutan-1-one and then rearranging the latter, in the presence of a catalyst, into a 2-(2&#39;,2&#39;,2&#39;-trihalogenoethyl)-4-halogenocyclobutan-1-one of the above formula; said 2-(2&#39;,2&#39;,2&#39;-trihalogenoethyl)-4-halogenocyclobutan-1-ones being valuable intermediates for the preparation of 2-(2&#39;,2&#39;-dihalogenovinyl)-cyclopropanecarboxylic acid and its insecticidally active esters; as well as the 2-(2&#39;,2&#39;,2&#39;-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the above formula and the intermediates utilized for their preparation.

RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 891,412, filedMar. 29, 1978, now abandoned.

The present invention relates to a process for the preparation of2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI ##STR2## in which one of the radicals R₁ and R₂ is methyl and theother is hydrogen or methyl, or R₁ and R₂ together are an alkylene grouphaving 2 to 4 carbon atoms, and X and Y are each chlorine or bromine.

The present invention also relates to the novel2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI which can be prepared by the process according to the invention andalso to novel intermediates which can be used for their preparation.

It is known that α-halogenocycloalkanones are converted on heating inthe presence of bases, such as alkali metal hydroxides and alkali metalalcoholates, to cycloalkanecarboxylic acids having the same number ofcarbon atoms, or esters thereof, with contraction of the ring (Favorskireaction). This reaction is the basis for an industrially importantprocess for the preparation of cyclopropanecarboxylic acid derivativesand their esters having an insecticidal action, i.e. the pyrethyroids,from α-halogenocyclobutanones. However, it was not possible to use thisprocess, which is technically simple to carry out, for the preparationof pyrethroids which are derived from2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid, sincecorresponding α-halogenocyclobutanones suitable for the preparation ofsuch cyclopropanecarboxylic acid derivatives were not available.

It has already been proposed to prepare α-halogenocyclobutanones byreacting a halogenoketene with an olefin. Processes of this type aredescribed, for example, in German Offenlegungsschrift 2,539,048 andBritish Pat. No. 1,194,604 and also in J. Amer. Chem. Soc. 87, 5257-5259(1965) and in Tetrahedron Letters No. 1, 135-139 (1966). This synthesisprinciple has not been used hitherto for the preparation ofα-halogenobutanones, which are suitable as intermediates for thepreparation of 2-(2',2'-dihalogenovinyl)-cyclopropane-carboxylic acidsand their esters having an insecticidal action. This is in particulardue to the fact that the synthesis possibilities which are conceivableon the basis of the abovementioned method, i.e.

(a) reaction of a halogenated olefin with a halogenoketene in accordancewith the equation: ##STR3## or

(b) reaction of an unhalogenated olefin with a halogenoketene inaccordance with the equation: ##STR4## the symbols R₁, R₂, X and Y inthe above equations being as defined under formula I, do not lead to the2-(2',2',2'-trihalogenoethyl-4-halogenocyclobutan-1-ones of the formulaI, which are required as intermediates, since the reaction according to(a) does not take place because of the deactivation of the olefin whichis associated with the substitution by halogen and the reactionaccording to (b) results in a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one which cannot beconverted into a 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid,or an ester thereof, using an alkali metal hydroxide or alkali metalalcoholate.

The object on which the present invention is based is, therefore, toprovide a process for the preparation of2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI which uses readily accessible starting materials and is simple tocarry out.

A further object on which the present invention is based is to makeavailable the 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-onesof the formula I, which have not been known hitherto and which onheating with strong bases, such as alkali metal hydroxides or alkalimetal alcoholates, give the corresponding2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivatives, withcontraction of the ring and, at the same time, the elimination of 2 molsof hydrogen halide, and also readily accessible intermediates which canbe used for the preparation of α-halogenocyclobutanones of the formulaI.

It has now been found that2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI can be prepared in a simple manner by reacting a2,4,4,4-tetrahalogenobutyric acid chloride of the formula II ##STR5## inwhich X and Y are as defined under formula I, in the presence of anorganic base with an olefin of the formula III ##STR6## in which R₁ andR₂ are as defined under formula I, to give a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV ##STR7## in which R₁, R₂, X and Y are as defined under formula I, andthen rearranging the latter, in the presence of a catalyst, into a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI.

The 2,4,4,4-tetrahalogenocutyric acid chlorides of the formula II arenovel compounds. They can be prepared in a manner known per se by addinga carbon tetrahalide of the formula V ##STR8## in which X and Y are asdefined under formula I, onto a compound of the formula VI

    CH.sub.2 ═CH--Z                                        (VI)

in which Z is chlorocarbonyl, carboxyl, alkoxycarbonyl having 1 to 4carbon atoms in the alkyl group, or cyano, and converting resultingcompounds of the formula VII ##STR9## in which X and Y are as definedunder formula I and Z is carboxyl, alkoxycarbonyl or cyano, intocompounds of the formula VII in which Z is chlorocarbonyl.

A further possibility for the preparation of2,4,4,4-tetrahalogenobutyric acid chlorides of the formula II comprisesadding a compound of the formula VIa ##STR10## in which Z is as definedunder formula VI, onto 1,1-dichloroethylene and converting resultingcompounds of the formula VIIa ##STR11## in which Z is carboxyl,alkoxycarbonyl or cyano, into compounds of the formula VIIa in which Zis chlorocarbonyl.

When adding a carbon tetrahalide of the formula V onto an acrylic acidderivative of the formula VI and also when adding a dichloroacetic acidderivative of the formula VIa onto 1,1-dichloroethylene, the carbontetrahalide of the formula V and, respectively, the dichloroacetic acidderivative of the formula VIa can be employed in the stoichiometricamount. Preferably, however, an excess of the carbon tetrahalide of theformula V or the dichloroacetic acid derivative of the formula VIa, forexample an approximately 0.5-fold to 2-fold molar excess, is used andthe carbon tetrahalide of the formula V can also serve as a solvent.

The adding of a carbon tetrahalide of the formula V onto a compound ofthe formula VI, and also the adding of a compound of the formula VIaonto 1,1-dichloroethylene, is carried out in the presence of catalysts.Suitable catalysts are metals of principal group VIII and sub-groupsVIa, VIIa and Ib of the periodic system, for example iron, cobalt,nickel, ruthenium, rhodium, palladium, chromium, molybdenum, manganeseand copper. These metals can be employed in the elementary form or inthe form of compounds. Suitable compounds of these metals are, forexample, oxides, halides, sulphates, sulphites, sulphides, nitrates,acetates, citrates, carbonates, cyanides and thiocyanates, and alsocomplexes with ligands, such as phosphines, phosphites, benzoin,benzoyl- and acetyl-acetonates, nitriles, isonitriles and carbonmonoxide.

Examples of compounds of the abovementioned metals which are suitable ascatalysts are: copper-II oxide, iron-III oxide, the bromides, and inparticular the chlorides, of Cu-I, Cu-II, Fe-II and Fe-III, and also thechlorides of ruthenium, rhodium, palladium, cobalt and nickel; Cu-IIsulphate, Fe-II sulphate and Fe-III sulphate; Cu-II nitrate and iron-IIInitrate; manganese-III acetate and copper-II acetate; copper-IIstearate; iron-III citrate; Cu-I cyanide; ruthenium-IIdichloro-tris-triphenylphosphine and rhodium tris-(triphenylphosphine)chloride; chromium acetylacetonate and nickel acetylacetonate, copper-IIacetylacetonate, iron-III acetylacetonate, cobalt-II acetylacetonate andcobalt-III acetylacetonate, manganese-II acetylacetonate and copper-IIbenzoylacetonate; iron carbonyl-cyclopentadienyl complex; molybdenumcarbonyl-cyclopentadienyl complex, chromium tricarbonyl-aryl complexes,ruthenium-II acetocomplex, chromium hexacarbonyl and molybdenumhexacarbonyl, nickel tetracarbonyl, iron pentacarbonyl, cobalt carbonyland manganese carbonyl.

Mixtures of the said metals with metal compounds and/or other additivescan also be used, such as copper powder in combination with one of theabovementioned copper compounds; mixtures of copper powder with lithiumhalides, such as lithium chloride, or with isocyanides, such astert.-butyl isocyanide; mixtures of iron powder with iron-III chloride,if desired with the addition of carbon monoxide; mixtures of iron-IIIchloride and benzoin; mixtures of iron-II chloride or iron-III chlorideand trialkyl phosphites; and mixtures of iron pentacarbonyl and iodine.

Preferred catalysts are iron-II salts and complexes and iron-III saltsand complexes and also iron powder, but in particular copper powder,copper-I salts and complexes and copper-II salts and complexes, such asCu-I chloride, Cu-II chloride, Cu-I bromide, Cu-II bromide, Cu-IIacetylacetonate, Cu-II benzoylacetonate, Cu-II sulphate, Cu-II nitrateand Cu-I cyanide.

Very particularly preferred catalysts are copper powder, copper-Ichloride and bromide and copper-II chloride and bromide, as well asmixtures thereof.

The said catalysts are generally used in amounts of about 0.01 to 10mol%, preferably 0.1 to 5 mol%, based on the compound of the formula IIIor the 1,1-dichloroethylene.

The addition reactions are carried out in an organic solvent. Suitableorganic solvents are those in which the catalysts are adequately solubleor which can form complexes with the catalysts, but which are inerttowards the starting compounds. Examples of such solvents arealkylnitriles, especially those having 1--5 C atoms, such asacetonitrile, propionitrile and butyronitrile; 3-alkoxypropionitrileshaving 1 to 2 C atoms in the alkoxy moiety, such as3-methoxypropionitrile and 3-ethoxypropionitrile; aromatic nitriles, inparticular benzonitrile; aliphatic ketones having, preferably, a totalof 3--8 C atoms, such as acetone, diethyl ketone, methyl isopropylketone, diisopropyl ketone and methyl tert.-butyl ketone; alkyl estersand alkoxyalkyl esters of aliphatic monocarboxylic acids having a totalof 2-6 C atoms, such as methyl formate and ethyl formate, methylacetate, ethyl acetate, n-butyl acetate and isobutyl acetate, and also1-acetoxy-2-methoxyethane; cyclic ethers, such as tetrahydrofuran,tetrahydropyran and dioxane; dialkyl ethers having 1-4 C atoms in eachalkyl moiety, such as diethyl ether, di-n-propyl ether and di-isopropylether; N,N-dialkylamides of aliphatic monocarboxylic acids having 1-3 Catoms in the acid moiety, such as N,N-dimethylformamide,N,N-dimethylacetamide, N,N-diethylacetamide andN,N-dimethylmethoxy-acetamide; ethylene glycol dialkyl ethers anddiethylene glycol dialkyl ethers having 1-4 C atoms in each alkylmoiety, such as ethylene glycol dimethyl ether, ethylene glycol diethylether and ethylene glcyol di-n-butyl ether, and diethylene glycoldiethyl ether and diethylene glycol di-n-butyl ether; andhexamethylphosphoric acid triamide (Hexametapol).

Preferred solvents are alkylnitriles having 2-5 C atoms and3-alkoxypropionitriles having 1 or 2 C atoms in the alkoxy moiety,especially acetonitrile and 3-methoxypropionitrile.

The reaction temperature is in general not critical and can vary withinwide limits. Preferably, the reaction temperatures are between about 60°and 200° C. and especially between about 80° to 170° C.

The compound of the formula VI or VIa which is used is preferablyacrylic acid chloride or, respectively, dichloroacetyl chloride. Byusing these compounds the desired 2,4,4,4-tetrahalogenobutyric acidchlorides are obtained by a direct route in the pure form and in highyields. Further preferred compounds of the formulae VI and VIa areacrylic acid and dichloroacetic acid, respectively. The free2,4,4,4-tetrahalogenobutyric acids obtained using these compounds cansubsequently easily be converted, in a manner known per se, to thecorresponding acid chlorides by reaction with inorganic acid chlorides,such as phosphorus trichloride, phosphorus pentachloride, phosphorusoxychloride, phosgene and thionyl chloride.

The esters or nitriles of a 2,4,4,4-tetrahalogenobutyric acid of theformula VII (Z=alkoxycarbonyl or cyano) which are obtained whencompounds of the formula VI or VIa in which Z is alkoxycarbonyl or cyanoare used are first hydrolyzed, in the presence of strong acids, such aconcentrated hydrochloric acid, to the corresponding free2,4,4,4-tetrahalogenobutyric acid and this is then converted to thecorresponding acid chloride in the abovementioned manner.

The 2,4,4,4-Tetrahalogenobutyric acid chloride of Formula II wherein Xis bromine and Y is chlorine, i.e. 2-chloro-4,4,4-tribromo butyryc acidchloride, can be prepared by reacting 4,4,4-tribromobutyric acid atfirst with an inorganic acid chloride to form 4,4,4-tribromobutyric acidchloride and subsequently chlorinating the latter in 2-position to form2-chloro-4,4,4-tribromo-butyric acid chloride.

The tribromobutyric acid used as starting material can be obtained byreacting bromoform with acrylonitrile and subsequently hydrolysing the4,4,4-tribromobutyronitrile formed (c.f. J.Amer.Chem. Soc. 67, 601-602(1945)).

As inorganic acid chlorides there can be used phosphorus trichloride,phosphorus oxychloride phosgene, thionyl chloride and oxalyl chloride.The reaction of 4,4,4-tribromobutyric acid with the inorganic acidchloride is advantageously carried out in the presence of a catalyticamount of dimethylformamide. An excess of the inorganic acid chloridecan be used as solvent.

The chlorination of 4,4,4-tribromobutyric acid chloride is carried outin the usual way. As chlorinating agents there can be used, for example,free chlorine or N-chlorosuccinimide. A preferred chlorinating agent isN:chlorosuccinimide. The chlorination can be performed immediately afterthe reaction of 4,4,4-tribromobutyric acid with the inorganic acidchloride in excess inorganic acid chloride as solvent without isolatingthe 4,4,4-tribromobutyric acid formed. However, a purer product isobtained if the 4,4,4-tribromobutyric acid chloride is isolated and thesubsequent chlorination is carred out separately. The chlorination isperformed at a temperature of from 40° to 90° C., preferably 60° to 70°C. Advantageously the chlorination is performed under irradiation withUV-light or in the presence of a compound producing free radicals, suchas dibenzoylperoxide of azoisobutyronitril.

The reaction of the 2,4,4,4-tetrahalogenobutyric acid chlorides of theformula II with olefins of the formula III is advantageously carried outin the presence of an inert organic solvent. Suitable solvents are, forexample, aromatic or aliphatic hydrocarbons, which can be halogenated,such as benzene, toluene, xylenes, chlorobenzene, dichloro- andtrichloro-benzenes, n-pentane, n-hexane, n-octane, methylene chloride,chloroform, carbon tetrachloride, 1,1,2,2-tetrachloroethane andtrichloroethylene. Further suitable solvents are cycloaliphatichydrocarbons such as cyclopentane or cyclohexane, cycloaliphatic ketonessuch as cyclopentanone and cyclohexanone, and also aliphatic ketones,aliphatic and cyclic ethers, alkylnitriles and 3-alkoxypropionitrileshaving 1 or 2 carbon atoms in the alkoxy group, especially acetonitrileand 3-methoxypropionitrile.

Particularly suitable solvents are aliphatic, cycloaliphatic andaromatic hydrocarbons, in particular alkanes having 5 to 8 carbon atoms,benzene and toluene, and especially n-hexane and cyclohexane.

However, excess olefin of the formula III can also serve as the solvent.

Suitable organic bases, in the presence of which the reaction of a2,4,4,4-tetrahalogenobutyric acid chloride of the formula II with anolefine of the formula III is carried out, are, for example, tertiaryamines, in particular trialkylamines having 1 to 4 carbon atoms, andespecially 2 to 4 carbon atoms, in each alkyl group, cyclic amines, suchas pyridine, quinoline, and N-alkyl-pyrrolidines, N-alkyl-piperidines,N,N-dialkylpiperazines and N-alkyl-morpholines or dialkylanilines having1 or 2 carbon atoms in each alkyl group, such as N-methylpyrrolidine,N-ethyl-piperidine, N,N'-dimethyl-piperazine, N-ethyl-morpholine andN,N-dimethylaniline, and also bicyclic amidines, such as1,5-diazabicyclo[5.4.0]undec-5-ene and 1,5-diazabicyclo[4.3.0]non-5-ene,and bicyclic diamines, such as 1,4-diazabicyclo[2.2.2]octane.

The reaction of 2,4,4,4-tetrahalogenobutyric acid chlorides of theformula II with olefin of the formula III is preferably carried out inthe presence of trialkyamines having 1 to 4 carbon atoms in each alkylgroup. Particularly suitable bases are triethylamine and pyridine.

The organic base is employed in at least the equimolar amount, or in aslight excess, based on the 2,4,4,4-tetrahalogenobutyric acid chlorideof the formula II.

The olefins of the formula III are likewise used in at least theequimolar amount, based on the 2,4,4,4-tetrahalogenobutyric acidchloride of the formula II. It is, however, generally advantageous touse an excess of the olefin, in which case the olefin can, as alreadymentioned, also serve as the solvent. When readily volatile olefins areused, the reaction can be carried out under pressure.

The olefins of the formula III are in particular those in which one ofthe radicals R₁ and R₂ is methyl and the other is hydrogen or methyl, orR₁ and R₂ together are an alkylene group having 2 to 3 carbon atoms,i.e. isobutylene, propene, methylenecyclopropane andmethylenecyclobutane. Isobutylene and methylenecyclopropane areparticularly preferred.

The reaction temperature can vary within wide limits. They are ingeneral between 0° and 200° C. and preferably between 20° and 160° C.

The 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-ones of theformula IV are also novel compounds. Catalysts which can be used for therearrangement of the2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-ones of the formulaIV, which are first obtained, into2-(2',2',2'-trihalogenoethyl)-4-cyclobutan-1-ones of the formula I areacids, bases or quaternary ammonium halides.

The rearrangement, according to the invention, of2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-ones of the formulaIV into 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of theformula I is unexpected and is not known in the case of cyclobutanonesmonohalogenated in the α-position. It is particularly surprising that noelimination of HX takes place at the trihalogenoethyl group when therearrangement is carried out in the presence of a basic catalyst. Therearrangement proceeds with excellent, and frequently quantitative,yield.

The rearrangement, according to the invention, of2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-ones of the formulaIV into 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of theformula I is preferably carried out in the presence of basic catalysts.The basic catalysts are organic bases, such as primary, secondary andespecially tertiary amines of the formula ##STR12## in which Q₁ is alkylhaving 1 to 8 carbon atoms, cycloalkyl having 5 to 6 carbon atoms,benzyl or phenyl and Q₂ and Q₃ independently of one another are hydrogenor alkyl having 1 to 8 carbon atoms. Suitable basic catalysts are, forexample, triethylamine, tri-n-butylamine, tri-isopentylamine,tri-n-octylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine,N,N-dimethyl-2-ethylhexylamine, N,N-diethylaniline and also cyclicamines, such as pyridine, quinoline, lutidine, N-alkylmorpholines, suchas N-methylmorpholines, N-alkylpiperidines, such as N-methyl- andN-ethyl-piperidine, N-alkylpyrrolidines, such as N-methyl- andN-ethyl-pyrrolidine, diamines, such asN,N,N',N'-tetramethylethylenediamine andN,N,N',N'-tetramethyl-1,3-diaminobutane, N,N'-dialkylpiperazines, suchas N,N'-dimethylpiperazine, bicyclic amines, such as1,4-diazabicyclo[2.2.2]octane, and bicyclic amidines, such as1,5-diazabicyclo[5.4.0]undec-5-ene and 1,5-diazabicyclo[4.3.0]non-5-ene,and finally polymeric basic compounds, such asp-dimethylaminomethylpolystyrene.

Further suitable basic catalysts for the rearrangement, according to theinvention, of a 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-oneof the formula IV into a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1one of the formula Iare phosphines, especially trialkylphosphines, for exampletributylphosphine.

Acid catalysts which can be used for the rearrangement of2-(2',2',2'trihalogenoethyl)-2-halogenocyclobutan-1-ones of the formulaIV into 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of theformula I are inorganic or organic proton acids. Suitable inorganicproton acids are, for example, hydrogen halide acids, such as hydrogenchloride, hydrogen bromide, hydrogen fluoride and hydrogen iodide,nitric acid, phosphoric acid and sulphuric acid. Preferred inorganicproton acids are hydrogen halide acids.

If acids or bases are employed in excess, they can also serve assolvents.

Furthermore, salts of proton acids, especially hydrogen halide acids,with ammonia or a nitrogen-containing organic base, and also quaternaryammonium halides, quaternary phosphonium halides and sulphonium halidescan be employed. Suitable nitrogen-containing organic bases arealiphatic, cycloaliphatic, araliphatic and aromatic primary, secondaryand tertiary amines, as well as heterocyclic nitrogen bases. Examplesare: primary aliphatic amines having up to 12 C atoms, such asmethylamine, ethylamine, n-butylamine, n-octylamine, n-dodecylamine,hexamethylenediamine, cyclohexylamine and benzylamine; secondaryaliphatic amines having up to 12 C atoms, such as dimethylamine,diethylamine, di-n-propylamine, dicyclohexylamine, pyrrolidine,piperidine, piperazine and morpholine; tertiary aliphatic amines,especially trialkylamines having 1-4 C atoms in each alkyl moiety, suchas triethylamine, tri-n-butylamine, N-methylpyrrolidine,N-methylmorpholine, 1,4-diazabicyclo[2.2.2]octane and quinuclidine;substituted or unsubstituted primary, secondary and tertiary aromaticamines, such as aniline, toluidine, naphthylamine, N-methylaniline,diphenylamine and N,N-diethylaniline; and also pyridine, picoline,indoline and quinoline.

Quaternary phosphonium halides which can be used are, for example:hexadecyltributylphosphonium bromide and methyl- andethyl-triphenylphosphonium bromide; and a sulphonium halide which can beused is, for example, trimethylsulphonium iodide.

Preferred salts are those of the formula ##STR13## in which M isfluorine, bromine or iodine and especially chlorine, Q₄ is hydrogen,alkyl having 1-18 C atoms, cyclohexyl, benzyl, phenyl or naphthyl andQ₅, Q₆ and Q₇ independently of one another are hydrogen or alkyl having1-18 C atoms, and also N-alkyl-pyridinium halides having 1-18 C atoms inthe alkyl, especially the corresponding chlorides.

Examples of such salts are: ammonium chloride, ammonium bromide,methylamine hydrochloride, cyclohexylamine hydrochloride, anilinehydrochloride, dimethylamine hydrochloride, di-isobutylaminehydrochloride, triethylamine hydrochloride, triethylamine hydrobromide,tri-n-octylamine hydrochloride, benzyl-dimethylamine hydrochloride,tetramethylammonium chloride, bromide and iodide, tetraethylammoniumchloride, bromide and iodide, tetra-n-propylammonium chloride, bromideand iodide, tetra-n-butylammonium chloride, bromide and iodide,trimethyl-hexadecylammonium chloride, benzyldimethylhexadecylammoniumchloride, benzyldimethyltetradecylammonium chloride, benzyl-trimethyl-,-triethyl- and -tri-n-butyl-ammonium chloride,n-butyl-tri-n-propylammonium bromide, octadecyltrimethylammoniumbromide, phenyltrimethylammonium bromide or chloride andhexadecylpyridinium bromide and chloride.

Additional co-catalysts which can be used are alkali metal halides, suchas potassium iodide, sodium iodide, lithium iodide, potassium bromide,sodium bromide, lithium bromide, potassium chloride, sodium chloride,lithium chloride, potassium fluoride, sodium fluoride and lithiumfluoride.

These co-catalysts catalyze the reaction even in the absence of theabove ammonium salts, but additions of open-chain or macrocyclicpolyethers (crown ethers) are then advantageous for a rapid course ofreaction. Examples of such crown ethers are: 15-crown-5, 18-crown-6,dibenzo-18-crown-6, dicyclohexyl-18-crown-6 and5,6,14,15-dibenzo-7,13-diaza-1,4-dioxa-cyclopentadeca-5,14-diene.

The amount of catalyst employed can vary within wide limits. In somecases it suffices if the catalyst is present in traces. In general,however, the catalyst is preferably employed in an amount of about 0.1to 15 percent by weight, based on the compound of the formula VI.

The rearrangement can be carried out either in the melt or in an inertorganic solvent. The reaction temperatures for the rearrangement in themelt are in general between about 60° and 150° C. and especially about80° and 130° C.

Suitable catalysts for the rearrangement in the melt are, in particular,the abovementioned organic bases, especially trialkylamines having 1-8 Catoms in each alkyl moiety; and also salts of hydrogen halide acids withammonia or organic nitrogen-containing bases, such as trialkylaminehydrochlorides and hydrobromides having 1-8 C atoms in each alkylmoiety, and very particularly tetraalkylammonium halides, in particularPG,23 tetraalkylammonium chlorides, bromides and iodides, having 1-18 Catoms in each alkyl moiety.

Examples of suitable inert organic solvents are aliphatic,cycloaliphatic or aromatic hydrocarbons, which can be nitrated orhalogenated, such as n-hexane n-pentane, cyclohexane, benzene, toluene,xylenes, nitrobenzene, chloroform, carbon tetrachloride,trichloroethylene, 1,1,2,2-tetrachloroethane, nitromethane,chlorobenzene, dichlorobenzenes and trichlorobenzenes; lower aliphaticalcohols, for examples those having up to 6 C atoms, such as methanol,ethanol, propanol, isopropanol, butanols and pentanols; aliphatic diols,such as ethylene glycol and diethylene glycol; ethylene glycol monoalkylethers and diethylene glycol monoalkyl ethers having, in each case, 1-4C atoms in the alkyl moieties, such as ethylene glycol monomethyl etherand ethylene glycol monoethyl ether, diethylene glycol monomethyl etherand diethylene glycol monoethyl ether; cyclic amides, such asN-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone andN-methyl-ε-caprolactam; amides of carbonic acid, such as tetramethylureaand dimorpholinocarbonyl; amides of phosphorous acid, of phosphoricacid, of phenylphosphonic acid or of aliphatic phosphonic acids having1-3 C atoms in the acid moiety, such as phosphoric acid triamide,phosphoric acid tris-(dimethylamide), phosphoric acid trimorpholide,phosphoric acid tripyrrolinide, phosphoric acidbis-(dimethylamide)-morpholide, phosphoric aciddimethylamide-diethylamide-morpholide, phosphorous acidtris-(dimethylamide) and the tetramethyldiamide of methanephosphonicacid; amides of sulphuric acid and of aliphatic or aromatic sulphonicacids, such as tetramethylsulphamide, the dimethylamide ofmethanesulphonic acid or p-toluenesulphonic acid amide;sulphur-containing solvents, such as organic sulphones and sulphoxides,for example dimethylsulphoxide and sulpholane; and aliphatic andaromatic nitriles, 3-alkoxypropionitriles, aliphatic ketones, alkyl andalkoxyalkyl esters of aliphatic monocarboxylic acids, cyclic ethers,dialkyl ethers, N,N-disubstituted amides of aliphatic monocarboxylicacids and ethylene glycol dialkyl ethers and diethylene glycol dialkylethers of the type mentioned under process stage 1).

For the rearrangement in the presence of an acid catalyst, polarsolvents are advantageously used, especially lower alcohols, such asmethanol, ethanol and butanols, N,N-dialkylamides of aliphaticmonocarboxylic acids having 1-3 C atoms in the acid moiety, especiallyN,N-dimethylformamide, or dialkylsulphoxides, such asdimethylsulphoxide.

In aprotic, strongly polar solvents, such as the abovementionedN,N-disubstituted amides of aliphatic monocarboxylic acids, cyclicamides, amides of carbonic acid, amides of phosphorous acid, ofphosphoric acid, of phenylphosphonic acid or of aliphatic phosphonicacids, amides of sulphuric acid or of aliphatic or aromatic sulphonicacids, and also dialkylsulphoxides, such as dimethylsulphoxide, thereaction also proceeds without the addition of base or acid. In thesecases, the solvent acts as the catalyst.

In general, however, when the rearrangement is carried out in thepresence of an inert organic solvent a catalyst is added, preferably anorganic base having a pK_(a) value of more than 9, especiallytrialkylamines having 1-8 C atoms in each alkyl moiety, such astriethylamine, tri-n-butylamine and tri-n-octylamine; and also hydrogenhalide acids, especially HCl and HBr, and tetraalkylammonium halides,especially tetraalkylammonium chlorides, bromides and iodides having1-18 C atoms in each alkyl moiety.

Particularly preferred solvents are aliphatic alcohols having 1-4 Catoms, toluene, xylenes, chlorobenzene, dioxane, acetonitrile,3-methoxypropionitrile, ethylene glycol diethyl ether and di-isopropylketone.

The reaction temperatures for the rearrangement in the presence of aninert organic solvent are in general between about 0° and 150° C. andpreferably between about 80° and 130° C.

By means of the process according to the invention, novel2-(2',2',2'-trihalogenoethyl)-4-halogeno-cyclobutan-1-ones of theformula I, which are substituted in the 3-position and are suitable asintermediates for the preparation of2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativessubstituted in the 3-position, are available in a simple manner and ingood yield, using readily accessible starting materials. The processaccording to the invention is especially suitable for the preparation of2-(2',2',2'-trichloroethyl)-4-halogenocyclobutan-1-ones of the formula Iwhich are substituted in the 3-position. The course of the processaccording to the invention is extremely surprising and completelyunforeseeable, since, when a 2,4,4,4-tetrahalogenobutyric acid chlorideof the formula II, or a halogenoketene formed therefrom in situ by theelimination of hydrogen chloride, is reacted with an olefin of theformula III, a 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-oneof the formula IV, which is unsuitable for further conversion into a2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativesubstituted in the 3-position, is first formed and this is thenconverted, by a novel rearrangement, not hitherto observed in the caseof cyclobutanones, monohalogenated in the α-position, into a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI, which is suitable for further conversion into a2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativesubstituted in the 3-position.

The 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acids substitutedin the 3-position, and their esters having an insecticidal action, whichcan be prepared using novel2-(2',2',2'-trihalogenoethyl)-4-chlorocyclobutan-1-ones of the formula Ias the starting materials, can be described by the following formulaVIII: ##STR14## in which X, R₁ and R₂ are as defined under formula I andR is hydrogen, alkyl having 1 to 4 carbon atoms or a group of theformula IX ##STR15## in which R₃ is oxygen, sulphur or a vinylene group,R₄ is hydrogen, alkyl having 1 to 4 carbon atoms, benzyl, phenoxy orphenylmercapto, R₅ is hydrogen or an alkyl group having 1 to 4 carbonatoms and R₆ is hydrogen, cyano or ethynyl, or, if one of the radicalsR₁ and R₂ is methyl and the other is hydrogen or methyl, R₃ is thevinylene group, R₄ is phenoxy and R₅ is hydrogen, also alkyl having 1 to5 carbon atoms.

The 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivatives ofthe formula VIII in which R is a group of the formula IX are suitablefor combating diverse animal on plant pests, especially insects. Theproperties, fields of application and use forms of these activecompounds are described in the literature (c.f., for example, Nature,246, 169-170 (1973); Nature, 248, 710-711 (1974); Proceedings 7thBritish Insecticide and Fungicide Conference, 721-728 (1973);Proceedings 8th British Insecticide and Fungicide Conference, 373-78(1975); J. Agr. Food Chem. 23, 115 (1973); U.S. Pat. No. 3,961,070; andGerman Offenlegungsschriften Nos. 2,553,991, 2,439,177, 2,326,077 andNo. 2,614,648).

The conversion of2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI into 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativesof the formula VIII is carried out in a manner known per se, by heatingin the presence of suitable bases. Examples of suitable bases are alkalimetal hydroxides and alkaline earth metal hydroxides, such as sodiumhydroxide, potassium hydroxide, calcium hydroxide and barium hydroxide.Alkali metal carbonates and bicarbonates and alkaline earth metalcarbonates and bicarbonates, such as calcium carbonate, bariumcarbonate, potassium carbonate, sodium carbonate, sodium bicarbonate andpotassium bicarbonate, can also be used as bases. Further suitable basesare alcoholates derived from the radical R according to the abovedefinition, especially the corresponding sodium alcoholates andpotassium alcoholates. The use of such alcoholates has the advantagethat the corresponding ester is obtained direct, whilst when alkalimetal hydroxides and alkaline earth metal hydroxides are used, the saltsof these bases with the 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylicacid formed are first obtained. These salts can, however, also beconverted into esters in a simple manner which is known per se, forexample by converting them into the corresponding acid chloride andreacting the latter with an alcohol derived from the radical R.

Depending on the nature of the base used, the conversion of a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI into a 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acidderivative of the formula VIII is advantageously carried out in anaqueous, aqueous-organic or organic medium. When the base used is analkali metal carbonate or alkaline earth metal carbonate, the reactionis carried out in an aqueous or aqueous-organic medium. The reaction inthe presence of alkali metal hydroxides or alkaline earth metalhydroxides and alkali metal bicarbonates is also advantageously carriedout in an aqueous or aqueous-organic medium. In this case, the free2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acids of the formulaVIII (R═H) are obtained after acidifying the reaction mixture, forexample by adding concentrated hydrochloric acid.

Suitable solvents for the conversion of2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI into 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativesof the formula VIII in an aqueous-organic or organic medium are loweralcohols, for example those having 1 to 6 carbon atoms, benzyl alcohol,aliphatic or cyclic ethers, such as diethyl ether, di-n-propyl ether,diisopropyl ether, tetrahydrofuran and dioxane, and also aliphatic,cycloaliphatic or aromatic hydrocarbons, such as n-pentane, n-hexane,cyclohexane, benzene, toluene and xylenes.

The conversion of2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI to 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivativesof the formula VIII is generally carried out at the boiling point of thereaction medium chosen. Reaction temperatures of between 40° and 120° C.are particularly suitable.

When 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of theformula I are converted into2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acid derivatives of theformula VIII, the corresponding2-(2',2',2'-trihalogenoethyl)-cyclopropanecarboxylic acid derivatives ofthe formula X ##STR16## in which R, R₁, R₂ and X are as defined, areformed as intermediates. These products can be isolated if the reactiontemperature is kept below 40° C. and/or a less than equivalent amount ofbase is used. Above 40° C., these intermediates are converted to thecorresponding 2-(2',2'-dihalogenovinyl)-cyclopropanecarboxylic acidderivatives of the formula VIII on the addition of further base, withthe elimination of HX.

The 2-(2',2',2'-trihalogenoethyl)-cyclopropanecarboxylic acidderivatives of the formula X can also be prepared photochemically from2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-ones of the formulaI, by irradiation with UV light, if necessary with the addition ofconventional sensitisers (for example ketones, such as acetone,cyclohexanone, benzophenone, acetophenone and higher alkylaryl ketones,thioxanthone and the like), in the presence of reagents containinghydroxyl groups, which at the same time can serve as solvents. Examplesof reagents containing hydroxyl groups are alkanols, such as methanol,ethanol and the like, and in particular water.

The process according to the invention is illustrated in more detail bythe following examples.

EXAMPLE 1

(a) Preparation of 2,4,4,4-tetrachlorobutyric acid chloride

452.5 g (5 mols) of acrylic acid chloride (technical grade purity), 1.5liters of carbon tetrachloride, 1.5 liters of acetonitrile and 30 g ofcopper-I chloride are kept at 115° C. for 24 hours. The reaction mixtureis filtered to give a clear filtrate and the latter is evaporated undera waterpump vacuum. The residue is distilled. This gives 922 g (76% oftheory) of 2,4,4,4-tetrachlorobutyric acid chloride; boiling point78°-80° C./11 mm Hg.

IR spectrum (CHCl₃) in cm⁻¹ : 1780 (C═O). NMR spectrum (100 MHz, CDCl₃)in ppm: 3.16-3.94 (m, 2H, CH₂); 4.84-4.96 (m, 1H, CH).

2,4,4,4-Tetrachlorobutyric acid chloride can also be prepared asfollows:

90.5 g (1 mol) of acrylic acid chloride, 0.5 liter of carbontetrachloride, 0.2 liter of butyronitrile and 3 g of copper powder areheated at 115° C. for 20 hours. The reaction mixture is filtered, thefiltrate is evaporated and the residue is distilled. This gives 167.8 g(69% of theory) of 2,4,4,4-tetrachlorobutyric acid chloride; meltingpoint: 80°-81° C./12 mm Hg. The spectroscopic data are identical tothose of the 2,4,4,4-tetrachlorobutyric acid chloride prepared accordingto paragraph 1.

If the copper powder is replaced by copper-I chloride and thebutyronitrile is replaced by 3-methoxypropionitrile and the procedure isotherwise identical, 2,4,4,4-tetrachlorobutyric acid chloride isobtained in a yield of 71% of theory.

226 g (1mol) of 2,4,4,4-tetrachlorobutyric acid [prepared in accordancewith Israeli Patent Specification 18,771=CA, 63, 13089e (1965)], 600 gof thionyl chloride and 1 ml of N,N-dimethylformamide are warmed at 50°C. for 2 hours and at 75° C. for 2 hours. After evaporating off theexcess thionyl chloride, the residue is distilled. This gives 227.6 g(93% of theory) of 2,4,4,4-tetrachlorobutyric acid chloride; boilingpoint 90°-91° C./15 mm Hg.

145.9 g (1.5 mols) of 1,1-dichloroethylene, 147.4 g (1 mol) ofdichloroacetyl chloride, 200 ml of acetonitrile and 3 g of copper-Ichloride are heated at 130° C. for 8 hours. The reaction mixture isevaporated and the residue is subjected to fractional distillation. Thisgives 2,4,4,4-tetrachlorobutyric acid chloride in the form of acolorless liquid; boiling point 78°-80° C./11 mm Hg. The spectroscopicdata of the substance obtained are identical to those of the2,4,4,4-tetrachlorobutyric acid chloride prepared according to paragraph1.

(b) Preparation of2-chloro-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutan-1-one

280 g of isobutylene are injected into 122 g (0.5 mol) of2,4,4,4-tetrachlorobutyric acid chloride in 600 ml of cyclohexane, in anautoclave. A solution of 51 g (0.5 mol) of triethylamine in 500 ml ofcyclohexane is pumped in at 65° C. in the course of 4 hours. Thereaction mixture is then kept at 65° C. for a further 3 hours. Thehydrochloride of triethylamine, which has precipitated, is filtered offand the filtrate is evaporated. The crystals thus obtained are filteredoff. This gives 79.4 g (60% of theory) of2-chloro-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutan-1-one with amelting point of 75°-76° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1805 (C═0).

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 1.42 and 1.45 (in each case1s, 6H and in each case 1 CH₃); 2.91-3.28 (m, 2H, CH₂); 3.37-3.76 (m,2H, CH₂).

¹³ C NMR spectrum (CDCl₃) in ppm: 196 (s, CO); 95.3 (s, CH₃); 80.8 (s,C-2); 57.0 (t, CH₂); 56.4 (t, CH₂); 37.9 (s, C-3); 25.1 (q, CH₃); 28.8(q, CH₃).

Elementary analysis for C₈ H₁₀ Cl₄ O (molecular weight 263.98):calculated C 36.40%; H 3.82%; O 6.02%; Cl 53.72%. found C 36.4%; H 3.9%;O 6.2%; Cl 53.5%.

(c) Preparation of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one

132 g (0.5 mol) of the resulting2-chloro-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutan-1-one aredissolved in 700 ml of toluene, 1 ml of triethylamine is added and themixture is boiled under reflux. After a reaction time of 13 hours, afurther 1 ml of triethylamine is added and the mixture is boiled for afurther 7 hours. After cooling, the reaction mixture is washed, firstwith dilute hydrochloric acid and then with water, dried and evaporated.The solidified residue (124 g; 94% of theory), which according to thinlayer chromatography is a single compound, is crystallized fromn-hexane. This gives 105.8 g of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one;melting point 56°-57° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1800 (c═0).

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 4.77 (d, J═2 Hz, 1H, H onC-4); 3.47 (m, 1H, H on C-2); 2.73-3.26 (m, 2H, CH₂); 2.63 (s, 3H, CH₃);1.14 (s, 3H, CH₃).

¹³ C-NMR spectrum (CDCl₃) in ppm: 197.0 (s, CO); 97.8 (s, CCl₃); 69.4(d, C-4); 60.6 (d, C-2); 49.5 (t, CH₂ -CCl₃); 36.8 (s, C-3); 27.4 (q,CH₃); 18.6 (q, CH₃).

Elementary analysis for C₈ H₁₀ Cl₄ O (molecular weight 263.98):calculated C 36.40%; H 3.82%; O 6.02%; Cl 53.72%. found C 36.6%; H 3.8%;O 6.2%; Cl 53.6%.

The above compound can also be prepared as follows: 2.64 g (0.01 mol) of2-chloro-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutanone and 220mg (0.0008 mol) of tetra-n-butylammonium chloride are stirred for 6.5hours at 124° C. The cooled melt is boiled up with hot n-hexane andfiltered to give a clear filtrate. As the filtrate cools, 2.19 g (83% oftheory) of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutanone with amelting point of 53°-56° C. precipitate.

(d) Preparation of2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acid

13.2 g (0.05 mol) of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one areadded to 150 ml of 10% strength sodium hydroxide solution and themixture is stirred intensively. After 5 minutes a clear solution hasformed and this is warmed at 100° C. (bath temperature) for 1 hour. Thereaction solution is washed with diethyl ether, acidified withconcentrated hydrochloric acid, with cooling, and extracted with diethylether. The ether phase is washed with water, dried over magnesiumsulphate and evaporated. According to the NMR spectrum, the solidresidue (10.35 g) consists of 80% by weight ofcis-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acidand 20% by weight oftrans-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylicacid. Crystallization from n-hexane gives the pure cis-acid; meltingpoint 85°-87° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1710 (CO), 1625 (C═C).

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 1.30 (s, 6H, 2×CH₃); 1.85(d, J═8.5 Hz, 1H, HC-1); 2.02-2.19 (m, 1H, HC-2); 6.17 (d, J═8 Hz, 1H,CH═CCl₂).

EXAMPLE 2

421 g of propylene, 244 g (1 mol) of 2,4,4,4-tetrachlorobutyric acidchloride and 1.25 liters of cyclohexane are initially introduced into a6.3 liter autoclave. A solution of 101 g (1 mol) of triethylamine in 1liter of cyclohexane is pumped in at 50° C. in the course of 4 hours andthe reaction mixture is then kept at 50° C. for 3 hours. The reactionmixture is filtered and the resulting filtrate is washed with dilutehydrochloric acid and then with water, dried over magnesium sulphate andevaporated. The residue is crystallised from n-hexane. This gives 77.2 gof 2-chloro-2-(2',2',2'-trichloroethyl)-3-methylcyclobutan-1-one;melting point 80°-81° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1785 (CO).

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 3.28-3.73 (m, 3H); 2.65-2.95(m, 2H); 1.43 (d, J=6.5 Hz, 3H, CH₃).

¹³ C NMR spectrum (CDCl₃) in ppm: 196.5 (s, CO); 95.1 (s, CCl₃); 77.8(s, C-2); 55.3 (t, CH₂ -CCl₃); 50.9 (t, C-4); 38.1 (d, C-3); 15.8 (q,CH₃).

1 ml of triethylamine is added to 50 g (0.2 mol) of the resulting2-chloro-2-(2',2',2'-trichloroethyl)-3-methylcyclobutan-1-one in 500 mlof toluene and the mixture is stirred for 18 hours at a bath temperatureof 120° C. After cooling, the reaction mixture is filtered to give aclear filtrate and the filtrate is washed, first with dilutehydrochloric acid and then with water, boiled up briefly with activecharcoal, filtered again and evaporated. Distillation of the residuegives 38.7 g (77% of theory) of2-(2',2',2'-trichloroethyl)-3-methyl-4-chlorocyclobutan-1-one; boilingpoint 130°-131° C./12 mm Hg.

IR spectrum (CHCl₃) in cm⁻¹ : 1805 (CO).

NMR spectrum (100 MHz, CDCl₃) in ppm: 1.20 (d, J=7 Hz, 0.6H, CH₃); 1.46(d, J=7 Hz, 0.45H, CH₃); 1.66 (d, J=6.5 Hz, 1.95H, CH₃); 2.1-3.5 (m,4H); 4.55 (dd, J=8 and 2 Hz, 0.65H, CH); 5.00 (dd, J=9 and 2.5 Hz, 0.15H, CH); 5.15 (dd, J=9 and 1.5 Hz, 0.2H, CH).

According to the NMR spectrum and the gas chromatogram, the compoundconsists of 3 stereoisomers in a weight ratio of 13:4:3.

10.5 g of the resulting2-(2',2',2'-trichloroethyl)-3-methyl-4-chlorocyclobutan-1-one arestirred with 100 ml of 10% strength sodium hydroxide solution for 50minutes. The solution which has formed is then heated at 100° C. for 1hour. The reaction mixture is then washed with diethyl ether andcarefully acidified with concentrated hydrochloric acid. It is thenextracted with diethyl ether. The ether extract is washed with water,dried over magnesium sulphate and evaporated. This gives2-(2',2'-dichlorovinyl)-3-methylcyclopropane-1-carboxylic acid; meltingpoint 75°-78° C. (recrystallised from n-hexane).

IR spectrum (KBr) in cm⁻¹ : 1685 (C═O), 1625 (C═C).

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 1.25 (d, J=5.5 Hz, 3H, CH₃);1.54-2.18 (m, 3H); 3.96 (d, J=8 Hz, 1H, CH-CCl₂).

EXAMPLE 3

A solution of 25.3 g (0.25 mol) of triethylamine in 50 ml of n-hexane isadded dropwise, in the course of 7 hours, with stirring, to a solution,which is kept under reflux, of 25 g (0.37 mol) of methylenecyclobutaneand 61.1 g (0.25 mol) of 2,4,4,4-tetrachlorobutyric acid chloride in 200ml of n-hexane. After the reaction mixture has been stirred under refluxfor a further 2 hours, it is freed, whilst still hot, from the ammoniumsalt formed, by filtration. The filtrate is concentrated to about 1/3its volume. On cooling,1-chloro-1-(2',2',2'-trichloroethyl)-spiro[3.3]heptan-2-one of theformula ##STR17## precipitates in a crystalline form; melting point93°-94° C.

IR spectrum (CCl₄) in cm⁻¹ : 1790 (C═O).

NMR spectrum (100 MHz, CDCl₃) in ppm: 1.70-2.80 (m, 6H); 3.15-3.60 (m,4H).

A solution of 27.6 g (0.1 mol) of the resulting1-chloro-1-(2',2',2'-trichloroethyl)spiro[3.3]heptan-2-one in 100 ml oftoluene, together with 0.93 g (5 mmols) of tributylamine, is refluxedfor 9 hours. The reaction mixture is then evaporated and the residue isdistilled in vacuo. This gives1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.3]heptan-2-one of theformula ##STR18## in the form of a slightly yellowish oil; boiling point85°-90° C./0.005 mm Hg; n_(D) ²⁰ =1.5242.

IR spectrum (film) in cm⁻¹ : 1795 (C═O).

NMR spectrum (100 MHz, CDCl₃) in ppm: 1.80-3.85 (m, 9H); 4.68, 4.93(each one d, together 1H).

11.0 g (40 mmols) of the resulting1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.3]heptan-2-one are stirredtogether with 95 ml (about 240 mmols) of 10% strength sodium hydroxidesolution for 6 hours at 95° C. After cooling, the mixture is washed withseveral portions of diethyl ether, acidified with sulphuric acid andextracted with diethyl ether. The ether extracts are evaporated afterdrying over sodium sulphate. A small amount of strongly polar impuritiesis eliminated by filtering the residue from ten times the amount byweight of silica gel (eluant n-hexane/diethyl ether in a volume ratio of1:1). After concentrating the filtrate,2-(2',2'-dichlorovinyl)spiro[2.3]hexane-1-carboxylic acid of the formula##STR19## is obtained in the form of a 2:1 cis/trans mixture; meltingpoint 121°-28° C.

IR spectrum (CCl₄) in cm⁻¹ : 1705 (C═O).

NMR spectrum (100 MHz, CDCl₃) in ppm: 1.60-2.60 (m, 8H); 5.34, 5.97(each one d, together 1H); 11.80-11.50 (broad s, 1H).

EXAMPLE 4

280 g of isobutylene are injected into 122 g (0.5 mol) of2,4,4,4-tetrachlorobutyric acid chloride in 600 ml of cyclohexane, in anautoclave. 51 g (0.5 mol) of triethylamine in 500 ml of cyclohexane arepumped in at 65° C. in the course of 4 hours. The reaction mixture isthen kept at 65° C. for 3 hours and then heated at 125° C. for 18 hours.During this time, 2.0 g of triethylamine in 50 ml of cyclohexane arepumped in every 3 hours. The reaction mixture is poured onto ice,acidified with hydrochloric acid and extracted with cyclohexane. Theevaporated extract is filtered in toluene/cyclohexane (1:1 mixture byvolume) through 1 kg of silica gel in order to remove strongly polarimpurities. The filtrate is evaporated and the residue is crystallizedfrom n-hexane. This gives 31.8 g of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one;melting point 56°-57° C.

EXAMPLE 5

(a) 26.1 g (99 mmols) of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutanone are addedto 260 ml of a 10% strength sodium hydroxide solution, at 11° C., withstirring. The temperature rises to 28° C. in the course of 2.4 hours andthen falls to 20° C. in the course of a further 2 hours. The reactionmixture is diluted with 200 ml of water, washed with diethyl ether,rendered strongly acid with concentrated hydrochloric acid and extractedwith diethyl ether. The extract is washed with water, dried overmagnesium sulphate and evaporated. This gives 24.3 g (100% of theory) ofa pale yellow residue (melting point 80°-81° C.), which consistsexclusively of cis- andtrans-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclopropanecarboxylicacid. The mixture can be separated into the pure cis and trans compoundsby fractional crystallization or by column chromatography.

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 2.75-3.33 (m, 2H); 1.50-1.97(m, 2H); 1.32 (s, 2×CH₃ cis); 1.27 and 1.38 (2×s, 2×CH₃ trans).

(b) 8.0 g (30.3 mmols) of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutanone in 400 mlof acetone and 100 ml of water are irradiated, through pyrex glass, witha Philipps HPK 125 watt lamp until no further starting material can bedetected by chromatography. The reaction mixture is evaporated and theresidue is worked up to the acid as indicated under (a). This gives 6.95g (93% of theory) of a cis/trans mixture of2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclopropanecarboxylic acid, thespectroscopic data of which are identical to those of the mixtureobtained according to (a).

(c) 24.55 g (0.1 mol) of2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclopropanecarboxylic acid aresuspended in 350 ml of 10% strength sodium hydroxide solution and thesuspension is stirred for 4.5 hours at a bath temperature of 100° C. Thereaction solution is washed with diethyl ether, acidified withhydrochloric acid and extracted with chloroform. The extract is washedwith water, dried over magnesium sulphate and evaporated. Aftercrystallization from n-hexane, 17.55 g (84% of theory) of colorless2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid areobtained.

EXAMPLE 6

145 g (0.5 mol) of 2-bromo-4,4,4-trichlorobutyric acid chloride, 280 g(5 mols) of isobutylene and 600 ml of cyclohexane are initiallyintroduced into an autoclave. 51 g (0.5 mol) of triethylamine in 500 mlof cyclohexane are pumped in at 65° C. in the course of 4 hours. Themixture is then stirred for a further 3 hours at this temperature. Thereaction mixture is filtered. The filtrate is evaporated and the residueis crystallized from n-hexane. This gives 74.5 g (48% of theory) of2-bromo-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutanone in theform of a light beige powder; melting point 46°-49° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1885 (CO).

¹ H NMR spectrum (100 MHz, pyridine-d₅) in ppm: 3.79 (AB, 2H, CH₂); 3.10(AB, 2H, CH₂); 1.37 and 1.42 (1s in each case, total 6H, CH₃ in eachcase).

¹³ C NMR spectrum (CDCl₃) in ppm: 196.8 (CO); 95.6 (CCl₃); 74.8 (C-2);56.5 and 56.3 (CH₂ in each case); 38.0 (C-3); 27.4 and 24.7 (CH₃ in eachcase).

20 g (0.065 mol) of2-bromo-2-(2',2',2'-trichloroethyl)-3,3-dimethylcyclobutanone and 5 g oftetrabutylammonium bromide are stirred for 30 minutes at 80° C. and for10 minutes at 100° C. The solidified melt is chromatographed on silicagel (elution with toluene/cyclohexane, 1:1).2-(2',2',2'-Trichloroethyl)-3,3-dimethyl-4-bromocyclobutanone, whichcrystallizes on standing, is obtained in this way: melting point 56° C.

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 4.99 (d, J=2 Hz, 1H, H onC-4); 3.58 (X moiety of ABX, additionally resolved with J=2 Hz, 1H, H onC-2); 3.05 (AB moiety of ABX, 2H, CH₂); 1.22 and 2.67 (1s in each case,3H in each case, CH₃ in each case).

¹³ C NMR spectrum (CDCl₃) in ppm: 196.7 (s, CO); 97.7 (s, CCl₃); 60.7(d, C-2); 59.8 (d, C-4); 50.0 (t, CH₂ -CCl₃); 36.4 (s, C-3); 27.6 (q,CH₃); 21.0 (q, CH₃).

A solution of 3.2 g of NaOH in 70 ml of water is added to 3.1 g (10.6mmols) of 2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-bromocyclobutanoneand the mixture is stirred for 2 hours. It is then stirred for a further3 hours at 100° C. The reaction mixture is washed with diethyl ether andacidified with dilute hydrochloric acid. This aqueous phase is extractedwith diethyl ether. The extract is washed with water, dried overmagnesium sulphate and evaporated. The residue is crystallized fromn-hexane. This gives 2.55 g ofcis-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid;melting point 86° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1710 (CO), 1625 (C═C).

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 1.30 (s, 6H, 2×CH₃); 1.85(d, J=8.5 Hz, 1H, HC-1); 2.02-2.19 (m, 1H, HC-2); 6.17 (d, J=8 Hz, 1H,CH═CCl₂).

EXAMPLE 7

90.5 g (1 mol) of acrylic acid chloride, 364.8 g (1.1 mol) of carbontetrabromide, 200 ml of acetonitrile and 5.0 g of copper-I chloride areheated at 115° C. for 6 hours. After cooling, the reaction mixture isdistilled direct. This gives 136.6 g (33% of theory) of2,4,4,4-tetrabromobutyric acid chloride; boiling point 135°-140° C., 12mm Hg.

350 ml of cyclohexane are saturated with isobutylene at room temperature(20°-25° C.). 42.2 g (0.1 mol) of 2,4,4,4-tetrabromobutyric acidchloride are dissolved therein. 10.1 g (0.1 mol) of triethylamine in 50ml of cyclohexane are then added dropwise at room temperature in thecourse of 2 hours, with stirring and under a gentle stream ofisobutylene. The resulting reaction mixture is stirred for 3 hours andwater is then added. The organic layer is separated off, washed withwater, dried over magnesium sulphate and evaporated. The residue isfiltered through silica gel (eluant: cyclohexane/toluene, 1:1 mixture byvolume). The filtrate is evaporated. The residue is crystallized fromn-hexane.

2-Bromo-2-(2',2',2'-tribromoethyl)-3,3-dimethylcyclobutanone isobtained; melting point 61°-63° C.

IR Spectrum (CHCl₃) in cm⁻¹ : 1780 (CO).

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 3.97 (AB, 2H, CH₂); 3.13 (AB,2H, CH₂); 1.51 and 1.61 (1s in each case, 3H in each case, CH₃ in eachcase).

¹³ C NMR spectrum (CDCl₃) in ppm: 196.7 (CO); 76.8 (C-2); 60.0 and 56.6(CH₂ in each case); 38.1 (C-3); 31.7 (CBr₃); 27.7 and 25.0 (CH₃ in eachcase).

9.6 g (21.8 mmols) of2-bromo-2-(2',2',2'-tribromoethyl)-3,3-dimethylcyclobutanone and 2.0 gof tetrabutylammonium bromide are stirred at 90° C. for 30 minutes. Thecooled melt is chromatographed on silica gel (elution withtoluene/cyclohexane, 1:1). This gives2-(2',2',2'-tribromoethyl)-3,3-dimethyl-4-bromocyclobutanone in the formof an oil which crystallizes slowly and which is recrystallized fromdiethyl ether/n-hexane; melting point 91°-93° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1795 (CO).

¹ H NMR spectrum (100 MHz, CDCl₃) in ppm: 4.96 (d, J=2 Hz, 1H, H onC-4); 3.12-3.67 (ABX, the X moiety additionally being resolved with J=2Hz, 3H, CH₂ --CH); 1.18 and 1.67 (1s in each case, 3H in each case, CH₃in each case).

¹³ C NMR spectrum (CDCl₃): 196.4 (s, CO); 63.2 (d, C-2); 59.9 (d, C-4);54.6 (t, CH₂); 38.4 (s, CBr₃); 36.4 (s, C-3); 27.8 and 21.3 (q in eachcase, CH₃ in each case).

700 mg (1.56 mmols) of2-(2',2',2'-tribromoethyl)-3,3-dimethyl-4-bromocyclobutanone are stirredwith a solution of 190 mg of NaOH in 5 ml of water, to which 0.5 ml ofdioxane has been added, for 2 hours at room temperature. The mixture isthen stirred for 1 hour at 80° C. The clear solution is worked up to theacid in the customary way. 410 mg (88% of theory) ofcis-2-(2',2'-dibromovinyl)-3,3-dimethylcyclopropanecarboxylic acid areobtained.

IR spectrum (CHCl₃) in cm⁻¹ : 1695 (CO).

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 6.70 (6d, J=8 Hz, 1H,CH-CBr₂); 1.82-2.14 (m, 2H); 1.30 and 1.33 (1s in each case, total 6H,CH₃ in each case).

EXAMPLE 8

10.1 g (0.1 mol) of triethylamine in 100 ml of cyclohexane are addeddropwise in the course of 2 hours, at 65° C., to a solution of 14 g(0.17 mol) of methylenecyclopentane and 26.4 g (0.1 mol) of2,4,4,4-tetrachlorobutyric acid chloride in 220 ml of cyclohexane, withstirring. The mixture is then stirred at this temperature for a further3 hours. The reaction mixture is washed with dilute hydrochloric acidand then with water, dried over magnesium sulphate and evaporated. Theresidue is crystallized from n-hexane. This gives 16.6 g of1-chloro-1-(2',2',2'-trichloroethyl)spiro[3.4]octan-2-one of the formula##STR20## melting point 70°-73° C.

IR spectrum (CHCl₃) in cm⁻¹ : 1775 (CO).

NMR spectrum (100 MHz, CDCl₃) in ppm: 1.60-2.30 (m, 8H); 3.08 (AB, 2H,CH₂); 3.60 (AB, 2H, CH₂).

12.0 g (0.041 mol) of1-chloro-1-(2',2',2'-trichloroethyl)spiro[3.4]octan-2-one are stirredwith 3.6 g of tetrabutylammonium chloride at a bath temperature of 125°C. After 1.5 hours, the reaction mixture is chromatographed on silicagel (elution with toluene/cyclohexane, 1:1). 9.7 g (81% of theory) of1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.4]octan-2-one of the formula##STR21## are obtained in this way in the form of a colorless oil.

IR spectrum (CHCl₃) in cm⁻¹ : 1800 (CO).

NMR spectrum (100 MHz, CDCl₃) in ppm: 4.87 (d, J=2 Hz, 1H, CHCl); 3.70(X moiety of ABX, additionally resolved with J=2 Hz, 1H, CH): 2.73-3.29(AB moiety of ABX, 2H, CH₂); 1.45-2.23 (m, 8H).

4.83 g (16.6 mmols) of1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.4]octan-2-one are added to asolution of 2.0 g of NaOH in 40 ml of water and 3 ml of dioxane and themixture is stirred for 2 hours at room temperature and then for 3 hoursat 100° C. The reaction solution is washed with diethyl ether andacidified with dilute hydrochloric acid. The acid solution is extractedwith diethyl ether. The extracts are washed with water, dried overmagnesium sulphate and evaporated. The residue is crystallized fromn-hexane. This gives 3.3 g of2-(2',2'-dichlorovinyl)spiro[2.4]heptane-1-carboxylic acid of theformula ##STR22## in the form of a white powder; melting point 90°-105°C.

IR spectrum (CHCl₃) in cm⁻¹ : 1705 (CO), 1620 (C═C).

NMR spectrum (100 MHz, CDCl₃ /D₂ O) in ppm: 6.15 (d, J=9 Hz, 0.8H,CH═CCl₃ cis); 5.51 (d, J=9 Hz, 0.2H, CH═CCl₂ trans); 2.00-2.40 (m, 2H);1.60-1.95 (m, 8H).

EXAMPLE 9

33.6 g (0.62 mol) of methylenecyclopropane and 152 g (0.62 mol) of2,4,4,4-tetrachlorobutyric acid chloride in 620 ml of n-pentane areinitially introduced into a 2.5 liter autoclave. 62.8 g (0.62 mol) oftriethylamine in 120 ml of n-pentane are pumped in in the course of 6hours, at 60° C., and the reaction mixture is then kept at 60° C. for 6hours. The reaction mixture is filtered, the filtrate is evaporated andthe residue is distilled in vacuo. The fraction having a boiling rangeof 45°-80° C./0.09 mm Hg is then chromatographed on 250 g of silica gelusing hexane/0-50% by weight toluene. The pure fractions are evaporatedand the residue is distilled. This gives1-chloro-1-(2',2',2'-trichloroethyl)spiro[3.2]hexan-2-one of the formula##STR23## having a boiling point of 70°-71° C./0.08 mm Hg.

IR spectrum (CHCl₃) in cm⁻¹ : 1776 (CO).

¹ H NMR spectrum (100 MHz CDCl₃) in ppm: 0.8-1.8 (m, 4H); 2.6-3.8 (m,4H).

A solution of 11.0 g (42 mmols) of1-chloro-1-(2',2',2'-trichloroethyl)spiro[3.2]hexan-2-one and 1.17 g(6.3 mmols) of tributylamine in 15 ml of toluene is refluxed for 5hours. After cooling, the reaction mixture is diluted with n-pentane.The mixture is washed with 2 N sulphuric acid and then with saturatedsodium chloride solution, dried over sodium sulphate and evaporated. Theresidue is distilled in vacuo. This gives1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.2]hexan-2-one of the formula##STR24## having a boiling point of 60° C./0.01 mm Hg.

IR spectrum (CCl₄) in cm⁻¹ : 1780 (CO).

NMR spectrum (100 MHz, CDCl₃) in ppm: 0.8-1.7 (m, 4H); 2.6-4.2 (m, 3H);4.75, 5.15 (one d in each case; together 1H).

7.1 g (27 mmols) of1-chloro-3-(2',2',2'-trichloroethyl)spiro[3.2]hexan-2-one, together with54 ml (about 135 mmols) of 10% strength NaOH, are refluxed for 2 hours.After cooling, the mixture is washed with several portions of diethylether, acidified with sulphuric acid and extracted with diethyl ether.The ether extracts are evaporated after drying over sodium sulphate. Asmall amount of strongly polar impurities is removed by filtering onsilica gel (eluant: diethyl ether). After concentrating the filtrate,2-(2',2'-dichlorovinyl)spiro[2.2]pentane-1-carboxylic acid of theformula ##STR25## is obtained as an approximately 3:1 cis/trans mixture;melting point 77°-78° C.

IR spectrum (CCl₄) in cm⁻¹ : 1675 (CO).

NMR spectrum (100 MHz, CDCl₃) in ppm: 0.8-2.85 (m, 6H); 5.56 and 6.11(one d in each case, together 1H); 10.8 (broad s, 1H).

The examples which follow describe the preparation of some insecticidalactive compounds.

EXAMPLE 10 Preparation of the m-phenoxybenzyl ester of2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acid

(a) 4.18 g (0.02 mol) of2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acid and20 ml of thionyl chloride are warmed at 70° C. for 3 hours. The excessthionyl chloride is then evaporated off, the residue is taken up in 100ml of benzene and the mixture is evaporated again. A solution of 4.0 g(0.02 mol) of m-phenoxybenzyl alcohol in 40 ml of absolute benzene isadded to this residue[2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acidchloride] and the mixture is warmed to 40° C. 2.2 g (0.022 mol) oftriethylamine in 10 ml of absolute benzene are added dropwise to thismixture in the course of one hour and the reaction mixture is stirredfor a further 1 hour at this temperature. The reaction mixture is washedwith dilute hydrochloric acid, dried over magnesium sulphate andevaporated. The residue is chromatographed on silica gel using diethylether/n-hexane as the eluant (1:4 mixture by volume). This gives them-phenoxybenzyl ester of2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acidhaving a refraction of n_(D) ²⁰ =1.5628.

(b) 5.28 g (0.02 mol) of2-(2',2',2'-trichloroethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one,dissolved in 25 ml of absolute dimethoxyethane, are added dropwise to asolution of 4.0 g (0.02 mol) of m-phenoxybenzyl alcohol, 0.5 g (0.021mol) of NaH and 40 ml of absolute dimethoxyethane. The reaction mixtureis then stirred for 1 hour at 45° C., 2.25 g (0.02 mol) of potassiumtert.-butylate are then added and the mixture is refluxed for 3 hours.After it has been discharged into water, it is acidified with dilutehydrochloric acid and extracted with benzene. The evaporated extract ischromatographed on silica gel using diethyl ether/n-hexane as the eluant(1:4 mixture by volume). This gives the m-phenoxybenzyl ester of2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropane-1-carboxylic acid inthe form of a viscous oil, which has the same properties as thesubstance obtained according to (a).

EXAMPLE 11 β-Cyano-m-phenoxybenzylcis-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate

(1) 10 g (0.047 mol) ofcis-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid in100 ml of benzene are stirred with 12.1 ml (0.141 mol) of oxalylchloride for 24 hours at room temperature. After evaporating thereaction solution, the brown residue is distilled under reducedpressure. This gives 9.1 g of a clear liquid; boiling point 50° C./0.04mm Hg. 3.0 g of this clear liquid are dissolved in 30 ml of toluene and2 ml of pyridine are added. 2.9 g of α-cyano-m-phenoxybenzyl alcohol in20 ml of toluene are added dropwise to this mixture at room temperatureand the reaction mixture is then stirred for a further 16 hours at roomtemperature. The reaction mixture is washed, first with water, then withsaturated sodium bicarbonate solution and subsequently with salt water,dried over magnesium sulphate and evaporated. The residue ischromatographed on silica gel (elution with diethyl ether/n-hexane,1:2). This gives pure α-cyano-m-phenoxybenzylcis-2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate as amixture of diastereomers. NMR spectrum (60 MHz, CDCl₃) in ppm; 1.20-1.43(m, 6H, CH₃); 1.67-2.35 (m, 2H, 2×CH); 6.25 (d, J=9 Hz, 1H, CH-CCl₂),6.40 and 6.45 (1s in each case, 0.5H in each case, CH-CN); 6.98-7.65 (m,9H).

EXAMPLE 12

7.8 g (0.1 mol) of absolute pyridine are added dropwise, at roomtemperature, to a solution of 22.75 g (0.1 mol) of crude2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid chloride[prepared according to Example 1a] and 21.5 g (0.1 mol) of3-phenoxy-α-hydroxyethylbenzene in 250 ml of absolute toluene. Thereaction mixture is stirred for 15 hours at room temperature (20°-25°C.), washed with dilute hydrochloric acid and then with water, dried(over sodium sulphate) and evaporated. The residue is chromatographed onsilica gel using n-hexane/diethyl ether as the eluant (1:1 mixture byvolume). This gives α-methyl-m-phenoxybenzyl2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate in the formof a colorless oil of n_(D) ²⁰ =1.563.

EXAMPLE 13

(a) Preparation of 4,4,4-tribromobutyric acid chloride

324,8 g (1 mole) of 4,4,4-tribromobutyric acid is added to 600 g ofthionylchloride and 1 ml of dimethylformamide and the whole is heated atfirst for 2 hours at 40° C. and subsequently for 3 hours at 75° C. Thenthe excess of thionyl chloride is evaporated and the residue isdistilled in vacuo. 360 g (95% of theory) of 4,4,4-tribromobutyric acidchloride, b.p. 71°-73° C./0,05 torr, is obtained.

(b) Preparation of 2-chloro-4,4,4-tribromobutyric acid chloride

To a solution of 343,2 g (1 mole) 4,4,4-tribromobutyric acid chloride in600 g of thionylchloride 266,0 g (2 mole) of N-chlorosuccinimide isadded portion wise at 60° C. while the reaction mixture is irradiatedwith a mercury high-pressure lamp. After addition of theN-chlorosuccinimide the reaction mixture is stirred for 5 hours at 60°C. while irradiation is continued. Then the thionyl chloride isevaporated and the residue is distilled in vacuo. 309.7 (82% of theory)of 2-chloro-4,4,4-tribromobutyric acid chloride, b.p. 59°-63° C./0,05torr is obtained.

(c) Preparation of2-(2',2',2'-tribromoathyl)-2-chloro-3,3-dimethylcyclobutan-1-one

90,6 g (0, 24 mole) of 2-chloro-4,4,4-tribromo-butyric and chloride and360 ml of cyclohexane are placed in an autoclave and 134 g (2,4 mole) ofisobutylene is introduce under pressure. Then a solution of 24,2 g (0,24mole) of triethylamine in 120 ml of cyclohexane is added at 65° C.during 4 hours and, after addition of the triethylamine, the temperatureis kept at 65° C. for additional 3 hours. Thereafter the triethylaminehydrochloride formed is filtered off and the solvent is evaporated. Theresidue is dissolved in a solvent mixture consisting of equal parts oftoluene and hexane and the solution is filtered over silica gel. Afterevaporation of the solvent from the filtrate 51,4 g (54% of theory) of2-(2',2',2'-tribromoethyl)-2-chlor-3,3-dimethylcyclobutan-1-one, meltingpoint 95°-97° C., is obtained.

IR spectrum (CCl₄) in cm⁻¹ : 1800 (CO).

¹ H-NMR spectrum (100 MHz, CDCL₃) in ppm: 1.39 and 1.41 (s. 3H);2,86-3,22 (m, 2H); 3,55-4,15 (m, 2H).

(d) Preparation of2-(2',2',2'-tribromoethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one

22,8 g (0,054 mole) of2-(2',2',2'-tribromoethyl)-2-chloro-3,3-dimethylcyclobutan-1-on isdissolved in 220 ml of absolute ethanol saturated with hydrogen chlorideand the solution is stirred for 5 hours at 80° C. Then solvent isevaporated until the volume of the reaction mixture is reduced to onethird of the starting volume and, after addition of water, the mixtureis extracted with ether. The etheral extract is washed at first withsaturated sodium chloride solution and subsequently with sodiumbicarbonate solution and thereafter dried over sodium sulphate. Theresidue obtained after evaporation of the ether is purified bychromatography on silica gel using toluene as eluent. After combinationof the pure fractions and evaporation of the solvent there is obtained17,1 g (75% of theory) of2-(2',2',2'-tribromoethyl)-3,3-dimethyl-4-chloro-cyclobutane-1-one,melting point 87°-89° C.

IR spectrum (CCl₄) in cm⁻¹ : 1805 (CO). ¹ H-NMR spectrum (100 MHz,CDCl₃) in ppm: 1,14 and 1,67 (s, 3H); 3,08-3,68 (m, 3H); 4,77 (d, 1H).

(2) Preparation of2-(2',2',-dibromovinyl)-3,3-dimethylcyclopropane-1-carboxylic acid

A mixture of 800 mg (0,02 mole) of2-(2',2',2'-tribromoethyl)-3,3-dimethyl-4-chlorocyclobutan-1-one and 5,6ml of 5% by weight of aqueous sodium hydroxide solution is stirred for18 hours at 0° C. and subsequently for one additional hour at 80° C.Then the reaction mixture is cooled to room temperature washed withdiethyl ether, acidified with concentrated hydrochloric acid andextracted with diethyl ether. The extract is washed with water and driedover magnesium sulphate. After evaporation of the diethyl ether there isobtained 0,59 g (100% of theoriy) of2-(2',2'-dibromovinyl)-3,3-dimethylcyclopropane-1-carboxylic acidconsisting to 80% of the cis-isomer and to 20% of the trans-isomer.

IR spectrum (CHCl₃) in cm⁻¹ : 1695 (CO).

¹ H-NMR spectrum (100 MHz, CDCl₃) in ppm: 1,25 (s, CH₃ group oftrans-isomer), 1,35 (s, CH₃ group of trans-isomer), 1,30 (s, CH₃ groupof cis-isomer); 1,31 (s, CH₃ group of cis-isomer); 1.62-2,30 (m, 2H);6,15 and 6,70 (d, ratio of intensity 1:4, integral=1H).

What is claimed is:
 1. A process for the preparation of a2-(2'-2'-2'-tri-halogenoethyl)-4-halogenocyclobutan-1-one of the formulaI ##STR26## in which one of the radicals R₁ and R₂ is methyl and theother is hydrogen or methyl, R₁ and R₂ together are an alkylene grouphaving 2 to 4 carbon atoms, and X and Y are each chlorine orbromine,which comprises reacting, at a temperature of from about 0°-200°C., a 2,4,4,4-tetrahalogenobutyric acid chloride of the formula II##STR27## in which X and Y are as defined under formula I, in thepresence of an organic base with an olefin of the formula III ##STR28##in which R₁ and R₂ are as defined under formula I, said base and saidolefin being, respectively, present in at least equimolar amountsrelative to said acid chloride, to give a2-(2',2',2-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV ##STR29## in which R₁, R₂, X and Y are defined under formula I, andthen rearranging the latter, in the presence of about 0.1 to 15%, byweight of said butane-1-one, of an acid, base or quaternary ammoniumhalide catalyst, into a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI; said rearrangement being conducted at a temperature of from about60°-150° C. when in a melt system and at a temperature of 0°-150° C.when in an inert organic solvent system.
 2. A process according to claim1, which comprises using 2,4,4,4-tetrachlorobutyric acid chloride as the2,4,4,4-tetrahalogenobutyric acid chloride of the formula II.
 3. Aprocess according to claim 1, which comprises using2-chlor-4,4,4-tribromobutyric acid chloride of the formula II.
 4. Aprocess according to claim 1, which comprises using an olefin of theformula III in which one of the radicals R₁ and R₂ is methyl and theother is hydrogen or methyl, or R₁ and R₂ together are an alkylene grouphaving 2 to 3 carbon atoms.
 5. A process according to claim 1, whichcomprises using isobutylene as the olefin of the formula III.
 6. Aprocess according to claim 1, which comprises usingmethylenecyclopropane as the olefin of the formula III.
 7. A processaccording to claim 1, which comprises carrying out the reaction of a2,4,4,4-tetrahalogenobutyric acid chloride of the formula II with anolefin of the formula III in the presence of pyridine or of atrialkylamine having 1 to 4 carbon atoms in each alkyl group and in thepresence of an inert organic solvent.
 8. A process according to claim 1,which comprises carrying out the reaction of a2,4,4,4-tetrahalogenobutyric acid chloride of the formula II with anolefin of the formula III in the presence of triethylamine.
 9. A processaccording to claim 1, which comprises using an inorganic or organicproton acid as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 10. A process according to claim 1, which comprises usinga hydrogen halide acid as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4- halogenocyclobutan-1one ofthe formula I.
 11. A process according to claim 1, which comprises usingan organic base as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 12. A process according to claim 1, which comprises usingan amine of the formula ##STR30## in which Q₁ is alkyl having 1 to 8carbon atoms, cycloalkyl having 5 to 6 carbon atoms, benzyl or phenyland Q₂ and Q₃ independently of one another are hydrogen or alkyl having1 to 8 carbon atoms, as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 13. A process according to claim 1, which comprises usinga salt of a proton acid with ammonia, a nitrogen-containing organic baseor a quaternary ammonium salt as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 14. A process according to claim 1, which comprises usinga salt of a hydrogen halide acid with an aliphatic, cycloaliphatic,araliphatic or aromatic primary, secondary or tertiary amine or aheterocyclic nitrogen base as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 15. A process according to claim 1, which comprises usinga salt of the formula ##STR31## in which M is fluorine, bromine oriodine and especially chlorine, Q₄ is hydrogen, alkyl having 1 to 18carbon atoms, cyclohexyl, benzyl, phenyl or naphthyl and Q₅, Q₆ and Q₇independently of one another are hydrogen or alkyl having 1 to 18 carbonatoms, or a N-alkylpyridinium halide having 1 to 18 carbon atoms in thealkyl group, as the catalyst for the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I.
 16. A process according to claim 1, which comprisescarrying out the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-cyclobutan-1-one of theformula I at temperatures of between 80° and 130° C.
 17. A processaccording to claim 1, which comprises carrying out the rearrangement ofa 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of theformula IV into a 2-(2',2',2'-trihalogenoethyl)-4-cyclobutan-1-one ofthe formula I in the melt at a temperature of between 80° and 130° C. inthe presence of a trialkylamine having 1 to 8 carbon atoms in each alkylgroup or of a tetraalkylammonium halide having 1 to 18 carbon atoms inthe alkyl groups.
 18. A process according to claim 1, which comprisescarrying out the rearrangement of a2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV into a 2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one ofthe formula I in the presence of an inert solvent.
 19. A processaccording to claim 1, which comprises carrying out the rearrangement ofa 2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of theformula IV into a2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI in an aliphatic alcohol having 1 to 4 carbon atoms, toluene, xylene,chlorobenzene, dioxane, acetonitrile, 3-methoxypropionitrile, ethyleneglycol, diethyl ether or diisopropyl ketone, as the solvent.
 20. A2-(2',2',2'-trihalogenoethyl)-2-halogenocyclobutan-1-one of the formulaIV ##STR32## in which one of the radicals R₁ and R₂ is methyl and theother is hydrogen or methyl, or R₁ and R₂ together are alkylene having 2to 4 carbon atoms, and X and Y are each chlorine or bromine.
 21. A2-(2',2',2'-trihalogenoethyl)-4-halogenocyclobutan-1-one of the formulaI ##STR33## in which one of the radicals R₁ and R₂ is methyl and theother is hydrogen or methyl, or R₁ and R₂ together are alkylene having 2to 4 carbon atoms, and X and Y are each chlorine or bromine.